chapter 3 rigid pavement - DOT On-Line Publications - Department ...

. C ‘i!\‘*A . . T’ECHSIC4L .UV?SORY T 5040.30
November 30, 1990
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the top of the dowel basket, as opposed to the bottom,
should stabilize the dowel basket once these spacer wires
are removed.
(3) Dowels should be lightly coated with grease or other
substance over their entire length to prevent bonding of the
dowel to the concrete. This coating may be eliminated in
the vicinity of the welded end if the dowel is to be coated
prior to being welded to the basket. The traditional
practice of coating only one-half of the dowel has
frequently resulted in problems, primarily caused by
insufficient greasing and/or dowel misalignment. The dowel
must be free to slide in the concrete so that the two
pavement slabs move independently, thus preventing excessive
pavement stresses. Only a thin coating should be used, as a
thick coating may result in large voids in the concrete
around the dowels.
(4) The placement of concrete at construction joints is
.particularly critical. Therefore, care must be taken to
ensure that only quality concrete is used in their
construction; i.e., do not use the first concrete down the
chute, nor the "roll" from the screed to construct this type
if joint. The concrete used to construct these joints
should be the'same as for the remainder of the slab.
practice of modifying the mix at the jo i nts is not
recommended.
The
(5) Careful and sufficient consolidation of the concrete $&the
area of the joints is essential to good joint performance.
Load transfer across a doweled joint is greatly affected'by
the quality of concrete consolidation around the dowels.
Consolidation also has a direct relationship to concrete
strength and durability. Concrete strength, in turn, has a
significant effect on the amount of spalling that occurs at
the joint.
(6) The placement of.dowels should be-carefully verified soon
after paving begins. If specified tolerances are not being
t . achieved, then an evaluation of the dowel'installation,
concrete mix design, and placement techniques must be made.
Appropriate corrections should be made to the paving process
to ensure proper alignment of the load transfer devices.
. '(7) When paving fulldepth full-width, a mechanical prespreader
and finishing machine in the paving train can be used to
reduce drag and shear forces on the dowels.
(81 In cases where separate concrete placement is made adjacent
to previously placed concrete, i.e., truck climbing lanes or
concrete shoulders being placed after mainline pavement, it
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